As is known in the art, there are many diverse applications wherein materials are to be mixed. Similarly, there are many manufacturing processes which require the cleaning or shake-out of parts such as castings, moldings or bulk material, with or without a working media. For both types of applications, it is useful to utilize a tumbling apparatus.
Some time ago, it was found that an improved finish could be obtained on cast or molded parts by adding a vibratory motion to the tumbling apparatus. For instance, in my earlier U.S. Pat. No. 3,157,004, an improved burnishing apparatus using a U-shaped tub mounted on trunnions was disclosed wherein vibratory force was applied directly to the U-shaped tub such that the force passed through the center of gravity of the tub. When the tub was tilted about the trunnions, the vibratory force was used to discharge the media and parts from the tub.
Although improved burnishing of the parts resulted from this use of vibratory motion through the center of gravity of the tumbling apparatus, problems continued with the balance of the machine. These included wear on bearings and the time it took to obtain the desired finish. To overcome such problems, a vibrating tumbling apparatus was conceived and developed as fully disclosed in my earlier U.S. Pat. No. 4,709,507.
According to that invention, a container is vibrated along small segments of an arcuate or circular path centered at a point offset from the center of the container. The material in the container is moved or conveyed and tumbled not only due to the coefficient of friction of the material with the surface of the container, but also due to the angle of attack between the material and the surface of the container at any given point because of the segmental circular path. While highly satisfactory tumbling action resulted from this improved arrangement, certain problems were discovered which required further attention.
In particular, my earlier U.S. Pat. No. 4,709,507 taught that the inner surface of the container may be coated or lined. More specifically, this coating or lining was taught as comprising a material having a particular coefficient of friction, which typically would comprise a material such as rubber or leather, which material was to aid in the conveying action and to improve the tumbling of the parts. In addition, the liner was recognized as comprising a wear surface which could be replaced when it had been worn.
Unfortunately, typical materials utilized because of their coefficient of friction usually have certain less than desirable physical characteristics. For instance, rubber or leather which is otherwise well suited for the intended purpose cannot withstand high temperatures and, thus, hot castings cannot immediately be treated in such a vibratory tumbling apparatus without the liner incurring substantial damage. Furthermore, depending upon the materials treated in the apparatus, the useful life of the liner is less than would normally be considered desirable.
In addition, in order to maximize the mixing, burnishing, etc., it is desirable for the material in the apparatus to experience the best possible tumbling action. Thus, when the vibratory tumbling apparatus utilizes a generally horizontally arranged cylindrical container, it is desirable for the material to be vibrated upwardly along the inside surface of the container to the maximum extent possible before the material falls back by gravity to a lower point in the container. However, while conveying action is enhanced by utilizing a carefully selected liner, e.g., rubber or leather, it would remain desirable to be able to convey the material to a higher point.
The present invention is specifically directed to overcoming the above stated problems and accomplishing the resulting objectives in a novel and simple manner.